AADE Speaker

Paul WisemanMidland Reporter-Telegram

Published 6:00 pm, Saturday, March 13, 2010

Increases in horizontal drilling in the Permian Basin has given rise to the use of a relatively new tool that reduces friction, according to the speaker at a recent American Association of Drilling Engineers meeting.

Timm Burnett is a product specialist for NOV Downhole, which markets the Agitator. The tool was nvented about six years ago by Andergauge Drilling Systems, part of Grant-Prideco, which was purchased by NOV Downhole in 2009.

The system uses a sort of "mini-mud motor" to rotate a valve plate with an offset hole attached to the end of a rotor. As the valve rotates it alternately opens and closes a corresponding valve opening in a stationary pipe filled with fluid. "As those two valves cross each other they create a pressure pulse, or a wave," Burnett explained in a phone interview. "That wave is what moves up and down the drill string."

"We run it in jointed pipe with a shock tool," Burnett continued, "and the reason is that the wave that's created from the hydraulic pulse is translated into a mechanical force by the shock tool."

When the wave goes into the shock tool it extends and releases the shock tool 1/8 to 3/8 of an inch at high speed, slinging the wave up and down the drill string. In coiled tubing the system simply shakes the coil itself instead of using a shock tool

This keeps (the drill string) moving so that no friction can form, letting it work more smoothly by decreasing the torque and the drag. "Overall footage per day can be increased if you're not fighting drag and fighting torque," he said, especially when the directional drill is in slide mode. "The wave we create is always actual, never lateral," Burnett added.

Company literature states that the tool can be used with roller cone bits or fixed cutter bits and it extends PDC life through fine weight transfer. Tool sizes range from 3-3/8 outside diameter to 9-5/8 OD.

Burnett feels the tool is useful in many applications besides drilling."Wherever you have friction in the hole in any operation, whether that be running casing, pulling casing, coiled tubing, drilling...retrieving packers, milling plugs...it has applications in all that." The tool has proved useful in all those categories.

While the tool is useful in many categories, horizontal drilling is its fastest growing application according to Burnett.

Permian Basin use of the tool has involved wells in several counties in New Mexico, including Chavez, Lea and Eddy.

The main reason for the tool's introduction into the Permian Basin was the purchase of Grant Prideco by NOV, said Burnett. "Before, we were pretty limited on people and limited pretty limited on resources and inventory," he recalled. "Once we became part of NOV we not only got this international footprint, we got access to all of their facilities," as well as the ability to stage tools.